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Farshad, Abbas,Akhondzadeh, S. Asian Australasian Association of Animal Productio 2008 Animal Bioscience Vol.21 No.12
Four experiments were conducted to study the following: i) the influence of different concentrations of sucrose (0.15, 0.3 and 0.5 M with osmolality of 308, 500 and 760 mOsm/kg, respectively) in diluents and control diluent (370 mOsm/kg) on intensity of motility and progressive motility of goat sperm without rehydration and freezing step in four incubation periods (0, 0.5, 2 and 4 h after dilution); ii) the influence of gradual dilution (in 3 steps) on improvements in ascertained results of the first experiment; iii) cryoprotective effects of different concentrations of sucrose (0.15, 0.22, 0.29 and 0.37 M with osmolality of 450, 560, 740 and 920 mOsm/kg, respectively) plus 7% glycerol and 20% egg yolk in basic diluent (Tris-Citric acid-Fructose) and iv) the effect of two concentrations of sucrose (0.15 and 0.22 M) with and without glycerol (7%). In experiment 1, we obtained better results for control diluent, 0.15 and 0.3 M sucrose supplemented diluents with 0 and 0.5 h incubation periods. In experiment 2, apart from a slight improvement, similar tendencies to experiment 1 were observed. In experiment 3, we obtained the best result for diluent with 0.22 M sucrose with regard to intensity of motility, progressive motility, live sperm and normal acrosomes ($40{\pm}4%$, $3.1{\pm}0.2$, $37{\pm}4%$ and $37{\pm}4%$, repectively). In experiment 4, we obtained the best result for diluent with 0.22 M sucrose plus 7% glycerol in regard to intensity of motility, progressive motility and live sperm ($39{\pm}3%$, $3.6{\pm}0.4$ and $41{\pm}4%$, respectively). The characteristic normal acrosomes in diluents without glycerol, i.e. diluents with 0.15 and 0.22 M sucrose showed better results ($39{\pm}8$ and $42{\pm}6%$ respectively). With regard to the release of hyaluronidase enzyme there were no significant differences between diluents (p>0.05). The results of the diluents with 0.15 and 0.22 M sucrose without glycerol were slightly lower than those with glycerol ($69{\pm}11$ and $70{\pm}11$ vs. $72{\pm}11$ and $70{\pm}11{\times}120{\times}10^6$ units $ml^{-1}$, respectively). In conclusion, the use of concentrated sucrose solutions showed that goat sperm can tolerate osmolality up to 560 mOsm (0.22 M) in the freezing period. In addition, glycerol proved to be a necessary cryoprotective agent in the cryopreservation of goat sperm, particularly for intensity of motility, progressive motility and live sperm.
Total domination number of central graphs
Farshad Kazemnejad,Somayeh Moradi 대한수학회 2019 대한수학회보 Vol.56 No.4
Let $G$ be a graph with no isolated vertex. \emph{A total dominating set}, abbreviated TDS of $G$ is a subset $S$ of vertices of $G$ such that every vertex of $G$ is adjacent to a vertex in $S$. \emph{The total domination number} of $G$ is the minimum cardinality of a TDS of $G$. In this paper, we study the total domination number of central graphs. Indeed, we obtain some tight bounds for the total domination number of a central graph $C(G)$ in terms of some invariants of the graph $G$. Also we characterize the total domination number of the central graph of some families of graphs such as path graphs, cycle graphs, wheel graphs, complete graphs and complete multipartite graphs, explicitly. Moreover, some Nordhaus-Gaddum-like relations are presented for the total domination number of central graphs.
Modified Green–Lindsay thermoelasticity wave propagation in elastic materials under thermal shocks
Farshad Shakeriaski,Maryam Ghodrat,Juan Escobedo-Diaz,Masud Behnia 한국CDE학회 2021 Journal of computational design and engineering Vol.8 No.1
In this study, a nonlinear numerical method is presented to solve the governing equations of generalized thermoelasticity in a large deformation domain of an elastic medium subjected to thermal shock. The main focus of the study is on the modified Green–Lindsay thermoelasticity theory, solving strain and temperature rate-dependent model using finite strain theory. To warrant the continuity of the finding responses at the boundary after the applied shock, higher order elements are adopted. An analytical solution is provided to validate the numerical findings and an acceptable agreement between the two presented solutions is obtained. The findings revealed that stress and thermal waves have distinct interactions and a harmonic temperature variation may lead to a systematic uniform stress distribution. Besides, a notable difference in the results predicted by the modified Green–Lindsay model and classic theory is observed. It is also found that the modified Green–Lindsay theory is more efficient in determining the wave propagation phenomenon. Furthermore, the findings established that thermal shock induces tensile stresses in the structure immediately after the shock, and the perceived phenomenon mainly depends on the defined boundary conditions. The results show that the strain rate can have a significant influence on the displacement and stress wave propagation in a structure subjected to thermal shock and these impacts may be more considerable with mechanical loading.
Farshad, A.,Amidi, F.,Khor, A. Koohi,Rashidi, A. Asian Australasian Association of Animal Productio 2011 Animal Bioscience Vol.24 No.2
Cryopreservation protocols induce partially irreversible damage to mammalian sperm plasma membranes. Previous studies have indicated that adding cholesterol to the plasma membrane, as cholesterol-loaded-cyclodextrins, improves cryosurvival of sperm. Therefore, the purpose of this study was to determine if treating sperm of Markhoz bucks with cholesterol-loaded-cyclodextrins (CLC) (0, 0.75, 1.5, 2.25 and 3 mg/ml diluted $240{\times}10^6$ sperm/ml) in Tris-citric acid-glucose diluents with and without egg yolk (containing 5% glycerol) would improve the post-thaw sperm quality. The motion characteristics were evaluated with a Computer Assisted System Analyzer (CASA); acrosome integrity and vitality were measured with the triple-stain technique. Samples were recovered before and after freezing by means of putting straws into $37^{\circ}C$ water for 30 sec and then parameters were assessed. The results showed that the treatments significantly affected motility, progressive motility, recovery rate, curvilinear velocity, beat cross frequency, live sperm with reacted acrosome, live sperm with unreacted acrosome, dead sperm with reacted acrosorne, and dead sperm with unreacted acrosome during freezing (p<0.05). However; no significant differences were found for average path velocity, straight line velocity, amplitude of lateral head displacement, straightness and linearity (p>0.05). The best results were observed for extender containing 2.25 mg/ml ($240{\times}10^6$ sperm/ml) CLC supplemented with 2.6% egg yolk. In conclusion, the findings of this study indicate improved Markhoz sperm viability and motility following treatment in the presence of egg yolk.
Concurrent impact of chipping and pitting damages in a locomotive power transmission system
Farshad Niksai,Mohammad Ali Rezvani 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.8
The reliability of power transmission systems in locomotives directly impacts trains' availability and running safety. The failure of gears, like pitting and chipping on teeth, is a common failure that can affect vehicle dynamics and reduce the system's safety and reliability. Based on the frequent visual inspections, the simultaneous occurrence of pitting and chipping on gear teeth are observed. It is the purpose of this research to investigate these defects and their possible coincidence. The dynamic response of the gear system to the presence of the pitting and chipping damages on one tooth, individually and concurrently, is theoretically and experimentally evaluated and compared. The dynamic interaction between the gear system and other elements, such as the traction motor and wheelset, is based on the operational conditions. The time-variant mesh stiffness is considered the primary internal excitation in the dynamics of the gear system. An analytical method based on the potential energy is used. The defects' coincidence effect on the dynamic response in time and frequency domains is studied. To measure the severity of the defects, some statistical parameters for different failure cases are calculated and compared. As a result, the parameters that exhibit the most sensitivity to the corresponding failure are introduced.
Farshad Hashemi Rezvani,Behrouz Asgarian 국제구조공학회 2014 Steel and Composite Structures, An International J Vol.16 No.2
In this research the effect of seismic design level as a practical approach for progressive collapse mitigation and reaching desired structural safety against it in seismically designed concentric braced frame buildings was investigated. It was achieved by performing preliminary and advanced progressive collapse analysis of several split-X braced frame buildings, designed for each seismic zone according to UBC 97 and by applying various Seismic Load Factors (SLFs). The outer frames of such structures were studied for collapse progression while losing one column and connected brace in the first story. Preliminary analysis results showed the necessity of performing advanced element loss analysis, consisting of Vertical Incremental Dynamic Analysis (VIDA) and Performance-Based Analysis (PBA), in order to compute the progressive collapse safety of the structures while increasing SLF for each seismic zone. In addition, by sensitivity analysis it became possible to introduce the equation of structural safety against progressive collapse for concentrically braced frames as a function of SLF for each seismic zone. Finally, the equation of progressive collapse safety as a function of bracing member capacity was presented.